Pressure-sensitive adhesive (PSA) tapes are virtually ubiquitous in the home and workplace. In one of its simplest configurations, a pressure-sensitive tape includes a backing layer and an adhesive layer attached to the backing layer. According to the Pressure-Sensitive Tape Council, pressure-sensitive adhesives are known to possess properties including the following: (1) aggressive and permanent tack, (2) adherence with no more than finger pressure, (3) sufficient ability to hold onto an adherend, and (4) sufficient cohesive strength to be removed cleanly from the adherend. Materials that have been found to function well as PSAs include polymers designed and formulated to exhibit the requisite viscoelastic properties resulting in a desired balance of tack, peel adhesion, and shear holding power. PSAs are characterized by being normally tacky at room temperature (e.g., 20° C. to 25° C.). Materials that are merely sticky or adhere to a surface do not constitute a pressure-sensitive adhesive; the term pressure-sensitive adhesive encompasses materials with additional viscoelastic properties.
One important class of pressure-sensitive adhesives are those with a methacrylic-based elastomeric material. (Meth)acrylic-based elastomeric materials have been described, for example, in the following patent references: EP Patent Application 2072594 A1 (Kondou et al.), U.S. Pat. No. 5,648,425 (Everaerts et al.), U.S. Pat. No. 6,777,079 B2 (Zhou et al.), and U.S. Patent Application Publication 2011/04486 A1 (Ma et al.).
The (meth)acrylic-based elastomeric material typically is selected to provide a pressure-sensitive adhesive that is stable under normal use conditions. In some applications, for example, it is desirable that the pressure-sensitive adhesive remains stable under conditions such as relatively high temperatures and/or relatively high humidity. In other applications, however, it is desirable that the pressure-sensitive adhesive can be easily removed at the end of its useful life. For example, it can be desirable to remove adhesive labels after use or to separate adhered parts and assemblies for recycling purposes.